ArcGIS studies and field relationships of Paleoproterozoic mafic dyke swarms from the south of Devarakonda area, Eastern Dharwar Craton, southern India: Implications for their relative ages
ArcGIS studies and field relationships of Paleoproterozoic mafic dyke swarms from the south of Devarakonda area, Eastern Dharwar Craton, southern India: Implications for their relative ages
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印度南部达尔瓦尔克拉通东部德瓦拉康达地区南部古元古代镁铁岩脉群的 ArcGIS 研究和现场关系：对其相对年龄的影响
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发表时间：
2015
期刊：
影响因子：
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通讯作者：
L. K. Sinha
中科院分区：
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作者：
A. Samal;R. Srivastava;L. K. Sinha
对来自达瓦尔克拉通东部 Devarakonda 地区南部的不同古元古代镁铁岩脉的 Google 地球图像和横切场关系进行了研究，以确定相对的侵位年龄。 Devarakonda 面积约 700 平方公里，显示出不同代基性岩脉之间壮观的交叉场关系，因此被选为本研究的对象。尽管有一些来自东达瓦尔克拉通的独特古元古代镁铁质岩脉的最新辐射年龄数据，但该研究区域没有类似的年龄数据。因此，利用横切现场关系和GIS技术，为研究区建立了不同基性岩脉的相对年龄关系，其显示的情况与东达尔瓦克拉通其他部分略有不同。研究表明，NE-SW 走向的镁铁质岩脉年龄最年轻（可能属于~1.89 Ga 岩脉群），而 NNW-SSE 走向的镁铁质岩脉就位年龄最老。此外，NNW-SSE 镁铁质岩脉比其他两个已识别的镁铁质岩脉群更古老，即 WNW-ESE (∼2.18 Ga) 和 N-S 走向 (∼2.21 Ga) 镁铁质岩脉群，因为这两个岩脉群与 NNW-SSE 岩脉交叉。它为存在一组新的镁铁质岩脉提供了证据，该岩脉比~2.21 Ga 更古老，并且可能比~2.37 Ga 群更年轻。目前的研究还支持存在两个具有相似趋势（ENE-WSW 到 NE-SW）但位于两个不同年龄（一个是~2.37 Ga，另一个是~1.89 Ga）的镁铁质岩墙群的存在。
Google Earth Image and cross-cutting field relationships of distinct Paleoproterozoic mafic dykes from south of Devarakonda area in the Eastern Dharwar Craton has been studied to establish relative emplacement ages. The Devarakonda, covering an area of ∼700 km2, shows spectacular cross-cutting field relationships between different generations of mafic dykes, and is therefore selected for the present study. Although some recent radiometric age data are available for distinct Paleoproterozoic mafic dykes from the Eastern Dharwar Craton, there is no analogous age data available for the study area. Therefore, relative age relationships of distinct mafic dykes have been established for the study area using cross-cutting field relationships and GIS techniques, which shows slightly different picture than other parts of the Eastern Dharwar Craton. It is suggested that NE–SW trending mafic dykes are youngest in age (probably belong to ∼1.89 Ga dyke swarm), whereas NNW–SSE trending mafic dykes have oldest emplacement age. Further, the NNW–SSE mafic dykes are older to the other two identified mafic dyke swarms, i.e., WNW–ESE (∼2.18 Ga) and N–S trending (∼2.21 Ga) mafic dyke swarms, as dykes of these two swarms cross-cut a NNW–SSE dyke. It provides an evidence for existence of a new set of mafic dykes that is older to the ∼2.21 Ga and probably younger to the ∼2.37 Ga swarm. Present study also supports existence of two mafic dyke swarms having similar trend (ENE–WSW to NE–SW) but emplaced in two different ages (one is ∼2.37 Ga and other ∼1.89 Ga).